mop ,mop(old)?

what are the differences between them ?
which one is less bugged?
which one is your advice ?
and the last question is both of them on frostwolt server?

Yeah, description are not best.
MoP should be MoP(with WoD Models)
While MoP(old) should be MoP.
I personally have MoP("old").

is it buggy too much(mop old)? or in acceptable level?

Yes its buggy